Airborne component extractor hood

ABSTRACT

An airborne component extraction system includes a source of a positive pressure air stream and a source of a negative pressure air stream. The air streams are directed through conduits to a hood that distributes the positive pressure air stream into a work area, and that draws the negative pressure air stream from the work area to remove airborne components within the work area. Aspects of the hood offer greatly enhanced performance in creating a controlled region for component removal and for drawing and removing the components for the work area.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Nonprovisional patent application of U.S.Provisional Application No. 61/737,653, entitled “Airborne ComponentExtractor”, filed Dec. 14, 2012; and Provisional Application No.61/611,885, entitled “Fume Extractor”, filed Mar. 16, 2012, which areherein incorporated by reference.

BACKGROUND

The present disclosure relates generally to systems for extractingairborne components from air streams, such as in welding, cutting, metalworking, wood working, and other applications.

A wide range of industrial, commercial, hobby and other applicationsresult in airborne components that can be removed with proper extractionand filtering. Metal working operations, for example, range fromcutting, welding, soldering, assembly, and other processes that maygenerate smoke and fumes. In smaller shops it may be convenient simplyto open ambient air passages or to use suction or discharge air fromfans to maintain air spaces relatively clear. In other applications,cart-type fume extractions are used. In industrial settings, morecomplex fixed systems may be employed for extracting fumes from specificworks cells, metal working locations, and so forth. In other settings,such as machine shops, woodworking shops, worksites where cutting,sanding and other operations are performed, dust, fumes, particulate andother types of airborne components may be generated that it may bedesirable to collect and extract from work areas and controlled spaces.

A number of systems have been developed for fume extraction, and acertain number of these are currently in use. In general, these usesuction air to draw fumes and smoke from the immediate vicinity of themetal working operation, and to filter the fumes and smoke beforereturning the air to the room or blowing the air to an outside space.Further improvements are needed, however, in fume extraction systems.For example, it would be useful to increase the effective ability of thesystems to draw the fumes and smoke from the metal working workspace.Moreover, it would be useful to increase the distance and expand thevolume over which the fume extractor can effectively remove fumes andsmoke.

BRIEF DESCRIPTION

The present disclosure provides improvements to extractors designed torespond to such needs. The techniques are based upon the use of apositive airflow in conjunction with a suction airflow that drawsairborne components out of the workspace for filtration. The innovationsset forth in the disclosure have a number of different facets, and maybe used in conjunction with one another to obtain particular synergiesand advantages, or separately in some cases.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatical representation of a fume extractor inaccordance with aspects of the present techniques;

FIGS. 1A and 1B illustrate certain presently contemplated variations onthe interconnection of components used to provide positive pressure airand draw fumes and smoke from an application;

FIG. 2 is a perspective view of an exemplary implementation of the fumeextractor in a cart-like apparatus;

FIGS. 2A and 2B are diagrammatical representations of fixed orsemi-fixed installations utilizing the techniques described herein;

FIG. 3 is a perspective view of an exemplary hood for directing positivepressure air flow to an operation and extracting fumes and smoke throughan inner shroud;

FIG. 4 is a similar hood provided with manual means for adjustingoutgoing air;

FIG. 5 is a similar representation of a further implementation of a hooddesigned to create a swirling air flow;

FIG. 6 is a further implementation of a hood employing a radial collarto assist in directing positive pressure air flow outwardly from thehood;

FIG. 7 is a diagrammatical section of an exemplary hood illustratingcertain dimensions that may be advantageous to provide a degree ofadjustability in the provision of air to and withdrawal of air from thehood;

FIG. 8 is an elevational view of a portion of a hood in accordance withcertain embodiments of the present techniques;

FIGS. 9 and 10 are detail views of parts of the hood of FIG. 8;

FIG. 11 is a broken perspective view of a coaxial conduit arrangementfor providing positive pressure air flow and suction flow;

FIGS. 12 and 13 are diagrammatical views of certain alternativeembodiments that include multiple hoods and/or nozzles;

FIGS. 14 and 15 are diagrammatical views of a currently contemplatedextraction cart in accordance with aspects of the present techniques;

FIGS. 16-20 are illustrations of parts of an exemplary manifold andsupport assembly for an arm of a cart of the type shown in FIGS. 14 and15;

FIG. 21 is a diagram illustrating generally a comparison of componentcollection regions with and without the innovations summarized in thepresent disclosure; and

FIGS. 22 and 23 are vector flow diagrams illustrating the flow of gas toand from the nozzle of the system illustrated in the previous figures.

DETAILED DESCRIPTION

Turning now to the drawings, and referring first to FIG. 1, anextraction system 10 is illustrated for extracting airborne components,such as smoke, fumes, particulate matter, and more generally, workspaceair as indicated by reference numeral 12 from a work area 14. In theillustrated embodiment the extraction system 10 comprises a base unit 16coupled to conduits 18 that channel air to and from a hood 20. The hoodis designed to be placed at or near (typically somewhat above) the area14 and, when the base unit is activated, serves to create region of airaround the area and to extract the workspace air, directing extractedair to the base unit for processing.

It should be noted that while in certain embodiments described in thepresent disclosure a stand-alone base unit 16, and in one presentlycontemplated embodiment a cart-type unit is described, the presenttechniques is not limited to any particular physical configuration. Moregenerally, innovations provided by and described in the presentdisclosure may be implemented into fixed or semi-fixed installations,such as those used in industrial, commercial, hobby, and other settings.That is, certain of the components of the base unit described herein mayserve multiple workspaces, work cells, weld cells, work locations andareas, and so forth, by common conduits that direct positive-pressureair to and channel air and airborne components from multiple workspaces.Operator controls, where provided as described below, may be positionedremotely from these workspaces, or within the workspaces for control offlow to and from the particular workspace.

It should be noted that the “airborne components” discussed in thepresent disclosure may include any substance that is borne by, suspendedin or otherwise carried by the air, or more generally the fluid presentin the area considered. Depending upon the application, the airbornecomponents may be in an aerosol form, such as solid, liquid or gaseousphase particles that are suspended in air. Such airborne components mayform smoke, fumes (including chemical fumes), of clouds present or givenoff by an operation ongoing in the area, whether or not visible to thehuman operators. In other applications, the airborne components may beat least temporarily airborne but not suspended in the air, such as inthe case of larger particulate, such as droplets, mist (e.g., from oils,coolants, and so forth), dust (e.g., from drywall, grain, minerals,cements, or other dust sources), chips, debris, and so forth. Thepresent techniques are directed to collecting and extracting any suchairborne components in the manners described. Similarly, reference ismade in this disclosure to “air” or “airborne”, although the fluid inwhich the airborne components are found and that is circulated by thesystem may be, more generally, a gaseous substance that need not containthe same constituents, or in the same ratios as found in atmosphericair. Such gasses are intended nevertheless be included in the term “air”or “airborne”. Moreover, it is presently contemplated that the sameprinciples of fluid dynamics and borne component removal may be appliedto other “fluids” than air or gasses (including liquids), and to thatextent the teachings of the present disclosure are intended to extend tothose applications.

Returning to FIG. 1, as illustrated the base unit 16 comprises a blower22, such as a squirrel-cage blower, driven by a drive motor 24. Thedrive motor is controlled by control circuitry 26 which may providedrive signals to the motor for fixed-speed or variable-speed operation.The base unit 16 may be designed to draw power from any source, such asthe power grid, battery sources, engine-generator sets, and so forth.The control circuitry 26 typically includes processing circuitry andmemory for carrying out drive operations as desired by the operator orin response to system inputs as described below. Accordingly, thecontrol circuitry 26 may communicate with an operator interface 28 forreceiving operator settings, speed settings, on-off commands, and soforth. Similarly, the control circuitry 26 may communicate with a remoteinterface 30 designed to receive signals from remote inputs, remotesystems, and so forth. The remote interface may also provide data tosuch remote systems such as for monitoring and/or controlling operationof the extraction system.

In the illustrated embodiments conduits 18 extending between the baseunit 16 and the hood 20 comprise a positive pressure air conduit 32 anda return air conduit 34. In general, the positive pressure air conduit32 provides air to the hood, while the return air conduit 34 is under anegative or slight suction pressure to draw air containing the airbornecomponents from the workspace. The air returning from the hood inconduit 34 may be directed through a suction filter 38 before beingre-introduced into the blower 22. As described below, the system mayalso include components designed to allow for adjustment of theindividual or relative flow rates of one or both of the positive andnegative pressure air streams.

In the embodiment illustrated in FIG. 1, the hood 20 comprises an outershroud 40 which is essentially a rounded bell in a present embodiment,as well as an inner shroud 42 positioned within the outer shroud 40. Thesidewall 44 of the outer shroud is spaced from the inner shroud sidewall46, and the inner shroud sidewall terminates in a lower peripheralflange 48. An annular space 50 is thus defined between the sidewalls 44and 46 of the outer and inner shrouds. Positive pressure air flowsthrough this annular space and is distributed within it, ultimatelyflowing downwardly as indicated by the arrows in FIG. 1 and impactingthe flange 48. The flange forces a generally radially outward flow ofair to form the air region 52. In a presently contemplated embodiment,the flange 48 is substantially perpendicular to the center line of theinner and outer shrouds, which are generally aligned coaxially with oneanother. It has been found that the substantially perpendicular, radialoutflow of air creates a very effective air region, allowing the hood tobe spaced a considerable distance from the workspace or workpiecepositions while still providing very effective evacuation of airbornecomponents.

As noted above, the present techniques may allow for adjustment of thepositive pressure air flow and/or the return air flow to optimizeoperation of the system. Several different techniques are presentlycontemplated for such adjustment. For example, in the embodimentillustrated in FIG. 1, a suction air adjustment 54 may be providedbefore the suction filter 38. This adjustment may comprise, for example,a bypass valve, a louver, or other mechanical device which may beadjusted to limit the flow of air from the suction filter and,consequently, the intake of air into the blower 22 from the ambientsurroundings. Similarly, a return air adjustment 56 may be provided thatmay be similarly configured to allow for adjustment for the flow rate ofreturning air. In some cases, this adjustment may allow some air to exitto the environment, as illustrated in FIG. 1. Such adjustment mayadvantageously allow for relative mass or volumetric flow rates of thepositive pressure and return airstreams to enhance creation of the airregion and extraction of workspace air. In an alternative configuration,manual adjustment of one or both of the suction and return air streamsmay be replaced by electronic control via inputs, designated byreference numeral 58. These may be provided on the base unit, such asthrough adjustment dials, membrane switches, operator touch controls,and so forth. Still further, manual and/or electronic adjustment of oneor both airstreams may be provided at the hood. In the embodimentillustrated in FIG. 1, for example, electronic inputs 60 are providedfor both adjustments. These are communicated to the remote interface 30of the base unit which, in turn, communicates them to the controlcircuitry 26. The control circuitry may be coupled to any suitabledevice, such as the suction and return adjustments 54 and 56 to regulatetheir operation (e.g., via small adjustment motors and actuatorassemblies). It should also be noted that adjustments to flow rates forthe positive and negative pressure airstreams may be made by alteringthe speed of one or more motors and/or blowers, fans or compressors.

It should also be noted that a system may be adapted to exchange datawith other system components, such as a welding/plasma cutting or othersystem 62. In the illustrated embodiment, the system 62 may comprise,for example, welding or plasma cutting power supplies, wire feeders,shielding gas supplies, and so forth. In other metal working settings,the system may include various other manual and machine tools. In stillother settings, the system may include various robots, production lines,power tools (e.g., saws, workstations, etc.). These will typically becoupled to the operation to accomplish the desired task on a workpiece64. Certain of these systems may be capable of providing control signalsto the extraction system to allow for turning the extraction system onand off, regulating speeds and air flows, and so forth. Suchcommunications may be provided via suitable cabling 66 or by other meansby wireless communications. An exemplary system designed to controloperation of a fume extractor is described, for example, in U.S. patentapplication Ser. No. 13/356,160, filed on Jan. 23, 2012, by Mehn et al.,and entitled “Fume Extractor for Welding Applications”, which is herebyincorporated by reference.

FIGS. 1A and 1B illustrate certain alternative configurations andinterconnections of the components of the base unit 16. In particular,as shown in FIG. 1A, the filter 38 may be placed downstream of theblower 22, and the suction adjustment 54 may direct air into the blowerdirectly. In this case, the filter 38 may discharge directly into thereturn adjustment 56. In the alternative of FIG. 1B, the suction filter38 is placed upstream of the suction adjustment 54, which here againdirects air into the blower.

Here again, it should be noted as well that although separate adjustmentmechanisms are described in connection with certain embodiments, asingle adjustment could be provided that allows for simply adjusting theratio of the flow rates, such as via a single knob or input at a baseunit, at the hood, or at any convenient location.

Moreover, other and additional components and functionalities may bebuilt into the system. For example, it is presently contemplated that atleast one of the components described above, or additional componentsmay provide for temperature regulation of the positive pressure airstream. For example, due to the significant assist offered by thepositive pressure region for airborne component removal, the operatormay desire to discontinue use of other fans, blowers and so forth in thework area. The positive pressure airstream may be cooled by one or morecomponents of the base unit (or centralized system) to provide not onlythe desired region surrounding the work area for component removal, butalso cooling for the operator. Heating in a similar manner may also beprovided.

FIG. 2 illustrates an exemplary embodiment of the system 10 implementedas a cart 68. The cart is designed to be rolled on wheel or casters 70to the vicinity of a metal working operation. As described above,conduits 32 and 34 direct positive pressure air to the hood 20 and drawsuction air back to the base unit. The base unit components describedabove are situated in or on the cart 68. The cart is designed to beplugged into a conventional outlet, such as to draw power from the powergrid. The embodiment illustrated in FIG. 2 comprises two positivepressure air conduits 32 positioned on either side of a return airconduit 34. All the conduits include flexible joints 72, allowingraising, lowering, lateral and other positioning of the hood at or near,typically above, the work space. Support structures, indicated byreference numeral 74, may assist in supporting the conduits and hood.All of these components may be retracted back towards the cart for easeof storage and transportation. Moreover, in the embodiment illustratedin FIG. 2 and as discussed in greater detail below, this arrangement ofconduits may make use of a manifold 76 that aides in distributingpositive pressure air flow to the annular space between the inner andouter shrouds of the hood.

As mentioned above, the present techniques may be employed in systemsand arrangements other than carts or systems and base units that arelocal to a work location. FIGS. 2A and 2B illustrate exemplary fixed orsemi-fixed systems of the type that may be employed in workshops,factories, assembly and metalworking plants, and so forth. In theembodiment of FIG. 2A, a positive air conduit 32 provides air from acommon air handling system, such as one equipped with a blower, filter,and any other components desired to provide air flow to multiple weldcells or other application locations. A negative air conduit 34similarly draws air from multiple application locations. In this sense,the conduits form headers or manifolds that may be positioned over thework areas or otherwise routed between them. Each work area, then, isprovided with a respective hood 20 for extracting fumes and smoke, aswell as respective suction and return adjustments 54 and 56. These mayoperate manually or electrically, as mentioned above in the case of thecart-type embodiment. FIG. 2B shows an alternative arrangement in whicha suction conduit is provided, but in which each work area has its ownlocal blower or fan. These may be provided either upstream or downstreamof a return adjustment 56, while a suction adjustment 54 is provided foradjustment the volumetric or mass flow rate of air and gas flowing tothe common header or manifold defined by conduit 34.

FIG. 3 is a more detailed view of an exemplary hood in accordance withcertain aspects of the present techniques. As shown in FIG. 3, the hood20 includes and outer shroud 40 and inner shroud 42 spaced from oneanother to allow for airflow as described above. Attachment components78 may be secured to the return air conduit (or one or more positivepressure air conduits) for supporting the hood on the conduits.Moreover, various mechanical structures, such as stand-offs 80 may beprovided for defining and maintaining the annular spacing between theouter shroud 40 and inner shroud 42. As will be appreciated by thoseskilled in art, flange 48 has an upper surface that is spaced from thelower peripheral edge of the outer shroud 40 to define an annularopening or gap 82. Positive pressure air flows down into the manifold76, is distributed by manifold around the annular spacing between theinner and outer shrouds, flowing downwardly through the annular spacingand outwardly through the opening or gap 82 to provide the desired airregion, as indicated by the arrows in FIG. 3. Various forms of manifoldsmay be provided, and these may accommodate one, two or more positivepressure airstream conduits. For example, two such inlets are providedin the manifold 76 of FIG. 3, and these may direct air or partially orfully around the annulus. In some embodiments, the shroud may beeffective to distribute the positive pressure air flow without the needfor a manifold. Another embodiments, diverting structures, baffles, andso forth may be provided in a manifold to generally equally distributethe incoming airflow around the hood.

FIG. 4 illustrates a further embodiment of a hood 20 designed to allowfor manual adjustment of positive airflow. As noted above, electroniccontrol inputs, such as push buttons, dials, and touch controls, may beprovided on the hood to channel signals via conductors or wirelessly tothe base unit, or more generally, to the location of the flow controldevices. However, manual control of one or more airstreams, may beprovided, such as illustrated in FIG. 4. In this embodiment, a movableouter shroud section 84 is provided immediately above the lower flange.The movable outer shroud section is mounted on one or more pins 86extending from either the inner shroud or a fixed outer shroud sectionas illustrated in FIG. 4. The movable outer shroud section 84 thuscomprises a slot 88 that is inclined and receives the pin 86. Wheremultiple pins are provided, multiple slots 88 may be used for mountingthe movable outer shroud section. The movable outer shrouds section 84may thus be rotated as indicated by reference numeral 90 to cause axialtranslation of the movable outer shroud section as indicated byreference numeral 92. This translation allows for adjustment of the airgap 94 between the movable outer shroud section and the flange 48,providing control of the mass or volumetric airflow of airregion-producing positive pressure airstream. Other structures may, ofcourse, be devised to provide for adjustment of this gap so as to permitregulation of air flow.

FIG. 5 illustrates a further embodiment of the hood designed to create aswirling air flow. In this case, the components of the hood may besubstantially similar to those described above, but in the annular spacebetween the outer shroud 40 and inner shroud 42 multiple helical fins 96are provided. The angle, width, extent, and so forth of these fins, inaddition to the number of fins, may be selected to impart a swirlingpattern to the outgoing air that creates the air region. The incline ofthe flange 48 may also be adjusted to enhance the creation of the airregion. Air flowing down through the annular space, then, has a downwardand outward directional component as well as a circumferentialcomponent, as indicated by arrows 98 in FIG. 5.

Still further, FIG. 6 illustrates an alternative configuration of thehood in which a radial collar 100 is positioned between a lowerperipheral edge of the outer shroud 40 and the flange 48. Such a collarmay be used to aide in directing the exiting air as it impacts and flowsover the flange 48.

It should be noted that the hood provided in all of theseimplementations may include a single flange for directing the positivepressure air radially outwardly, thereby significantly facilitatingmanufacture of the hoods and reducing their weight. In certain presentlycontemplated embodiments, for example, the outer and inner components ofthe hood are molded or otherwise formed separately, and then assembledby simply inserting the inner component into the outer and securing itin place, with the single flange spaced from the lower periphery of theouter component.

It should also be noted that the adjustability of the volumetric or massflow rates of positive and negative pressure air streams provides asignificant improvement over other fume and smoke or more generally,airborne component extractors. It has been found that the ability tostrike a balance between the flow of positive pressure air into theregion surrounding the work area and the flow of negative pressure airdrawn from the work area results in an extremely flexible system thatcan be adapted to the needs of the user, while providing enhancedcomponent removal at greater distances from the work than previoussystems.

There are several ways in which the best ratio or balance betweenpositive and negative pressure air flows may be qualified, with thisratio being adjustable by adjustment of the air flow parameters. Forexample, the ratio provided by:

$R = \frac{\begin{matrix}{{positive}\mspace{14mu} {pressure}\mspace{14mu} {airstream}\mspace{14mu} {flow}\mspace{14mu} {rate} \times} \\{{positive}\mspace{14mu} {pressure}\mspace{14mu} {airstream}\mspace{14mu} {velocity}}\end{matrix}}{\begin{matrix}{{negative}\mspace{14mu} {pressure}\mspace{14mu} {airstream}\mspace{14mu} {flow}\mspace{14mu} {rate} \times} \\{{negative}\mspace{14mu} {pressure}\mspace{14mu} {airstream}\mspace{14mu} {velocity}}\end{matrix}}$

has been found to provide a good indication of the effectiveness of fumeevacuation. The positive pressure airstream velocity may be measured,for example, at the region between the lower periphery of the outershroud and the peripheral flange of the inner shroud. The negativepressure airstream velocity may be measured, for example, at the inlet(lower opening) of the inner shroud. Such locations offer a convenientand standard place to compare air movement parameters. In presentlycontemplated embodiments, the ratio R is advantageously between about0.25 and 100, and it is believed that the ratio is particularlyadvantageously between about 0.6 and 10.

It should also be noted that particularly good performance has beenfound to result from particular ratios of mass or volumetric flow ratesof the positive and negative pressure airstreams. For example, incurrently contemplated embodiments, these airstreams may have mass orvolumetric flow ratios (positive-to-negative airstream ratios) ofbetween approximately 1:1 and 0.5:1, with a ratio of approximately 0.8:1being used in a present configuration. As disclosed above, these flowrates may be obtained by system design (e.g., the sized of theconduits), but also by intaking additional air to the blower from theenvironment, or expelling air from the blower, each of which may, wheredesired, be adjustable.

Performance may be improved as compared to conventional evacuationsystems, and optimized in the current techniques by appropriateselection and sizing of the system components, particularly of theconduits used to convey the airstreams to and from the work area. Forexample, in a currently contemplated design based on co-axial conduits,described below, an inner conduit has a nominal diameter of 7 inches, ora cross-sectional area of approximately 38 in², while the outer conduithas a nominal diameter of 10 inches, or a cross-sectional area ofapproximately 79 in², such that the annular area for the outgoingairstream has a cross-sectional area of approximately 41 in².

It is believed that a ratio of the outgoing flow area to the return flowarea of between approximately 4:1 and 0.7:1 may be particularly optimalfor obtaining the best airborne component removal. In a presentconfiguration, the ratio is between approximately 1:1 and 1.5:1. As willbe appreciated by those skilled in the art, the flow areas selected maycontribute significantly to the total static head required of the bloweror blowers, and this may be one of the design factors leading to theratios specified.

Further, it has been found that for a single-flange hood of the typediscussed, certain dimensional relationships may provide for optimalcomponent removal. FIG. 7 illustrates such a hood, diagrammatically, inwhich an effective inner diameter of the inner shroud 42 bears aparticular relation to the outer effective diameter of the flange of theinner hood. In particular, a ratio of the effective inner diameter 102of the inner shroud to the effective diameter 104 of the flange isadvantageously between about 0.25 and 0.75, and is believed to beparticularly advantageously about 0.5. By way of example, in a presentembodiment, the inner diameter 102 is about 8 inches, while the outerdiameter 104 is about 16 inches. It should be noted that the term“effective diameter” is used here to accommodate cases in which theshape of the inner shroud is not a right cylinder, or where either thisshape or the shroud shape is other than circular in section.

FIG. 8 illustrates a particular implementation for the hood of the typeshown in FIG. 7. The hood illustrated in FIG. 8 has an outer shroud 40and inner shroud 42 as described above. In this particular embodiment,the outer shroud 40 has a nominal diameter 106 of 10 inches, and theinner shroud 148 has a nominal diameter of 7 inches. The flangeextending from the inner shroud has a nominal diameter of 110 of 18inches. The outer shroud 140, moreover, has a radiused lip as bestillustrated in FIG. 9. This lip, indicated generally by referencenumeral 112, aids in smooth redirection of the airstream from theannular area between the outer shroud and inner shroud. In theembodiment illustrated in FIG. 9, the lip 112 has a radius of 0.25inches as indicated by reference numeral 114, and extends to an angle116 of approximately 45 degrees. It should be noted that in someembodiments, the lip on the outer shroud may be extended to form aflange much like that on the inner shroud, forming a sort of “doubleflange” structure. As illustrated in FIG. 10, the outer flange of theinner shroud has a similar radius to promote smooth redirecting of theair flow both out of the angular area between the shrouds and back intothe inner shroud. In the illustrated embodiment, two radiuses arepresent at this transition point, a first radius 118 of approximately 2inches, followed by a larger radius of approximately 7 inchestransitioning to a generally flat section which is approximatelyperpendicular with the centerline of the shroud.

As discussed above, various configurations of conduits, numbers ofconduits and so forth may be envisaged. FIG. 11 represents, for example,conduits arrangement in a generally coaxial or tube-in-tube arrangement.Such arrangement may facilitate mounting, routing, supporting andhandling of the hood with respect to the base unit. In the embodimentshown in FIG. 11, for example, an outer conduit 122 has positionedgenerally coaxially within it an inner conduit 124 to produce an annularflow space 124. In this embodiment, positive pressure air flows throughthe annular space, with return air flowing through the inner conduit. Itmay be desirable to place standoffs or other fixed structures betweenthese conduits to maintain them spaced between one another, or in somearrangements these may be dispensed with and the conduits allowed to bemore or less freely disposed one within the other.

It should be noted that, while reference has been made to a singlenozzle having inner and outer shrouds, certain adaptations may be madeto the system without deviating from the techniques discussed in thepresent disclosure. For example, FIGS. 12 and 13 illustrate variationsin which multiple shrouds or nozzles may be used for positive pressureair flow and/or negative pressure air flow. In the illustration of FIG.12, two hoods 20 are illustrated adjacent to a source 30 from whichfumes, gasses, particulate matter and so forth are to be drawn. Thesemay be coupled to the same or to a different system, which again may becart-like extractor or a fixed installation. As shown in FIG. 13, insome embodiments the positive flow and extraction flow may be separated.In this embodiment, multiple blower nozzles 132 are shown separated froman extraction conduit 134. In such embodiments, nozzles 132 may bepositioned in any desired manner around a source 130. In certainembodiments, for example, there may be positioned radially around thesource, with one or more extraction conduits being positioned adjacentto the outflow nozzles, such as in a central position.

FIGS. 14 and 15 illustrate they currently contemplated arrangement for asystem as described above in a cart-like product. The cart, designatedgenerally by reference numeral 136, includes a base unit 16 generally ofthe type described above. In this particular embodiment, an arm 138extends from the base unit and includes concentrically positionedconduits as described above. The arm provides both a positive pressureor outgoing flow and a return flow that may contain airborne componentsto be extracted from the work area. In this embodiment the arm 138 isadapted for rotation as indicated by arrow 140. The arm may rotate moreor less than 360°, and in a present embodiment rotation is limited tosomewhat less than the 360°, although full multi-rotation capabilitiesmay be designed into the joint between the arm and the base unit.

In the embodiment of FIG. 14, the arm 38 has a lower joint 142 where itjoins the base unit, a middle joint 144 that joins two generally linearsections of conduit and a hood joint 146 about which the hood 120 may bepivoted at least within a limited angular range. A support structure 148is provided adjacent to the lower joint 142 to aid in supporting the armas it is extended toward and retracted from a work area. A similarsupport 150 is provided adjacent to joint 144. In presently contemplatedembodiments, the joints include smooth inner walls that can be deformedso as to permit extension, retraction and, more generally, positioningof the arm with respect to the base unit, while adding little or no headloss as compared to a linear section of conduit. A manifold and supportassembly 152 is provided at a top section of the cart and aids intransitioning return flow and outgoing flow to and from the cart asdescribed more fully below. The manifold and support assembly 152 alsoaids in mechanically supporting the arm on the cart as it is extended,retracted, and rotated.

Within the cart, return flow enters a filter box 154 where it isfiltered to remove fine and larger particulate matter and othercomponents borne by the airstream. The assembly may be designed forpressure cleaning, in a process that may direct pressurized air againstone or more filter elements to promote the release of the capturedparticulate. From the filter box 154, air is drawn into the blower 22which is driven by a motor 24 as described above. The blower dischargesto a turn or elbow 156 that directs outgoing flow to the manifold andsupport assembly 152. It should be noted that in some embodiments, oneor more motors and/or blowers may be employed. For example, one motorand blower set may be used for the outgoing or positive air stream,while another motor and blower set may be used for the return ornegative air stream.

It is believed that greatly enhanced performance is obtained by thedesign of the cart in which as few as possible turns are provided in theincoming and outgoing flows. That is, as best illustrated in FIG. 15,the incoming flow is virtually linear from the arm to the filter box 154as illustrated by arrow 158. Air within the filter box is nearly static,depending upon the size of the filter box and the flow rate of the air.Thus, a bend may be considered to occur in the filter box, although froma practical standpoint in a current embodiment little or no head lossoccurs at this point. Flow from the filter box, indicated by arrow 160,enters the fan or blower 22, and exits as indicated at reference numeral162. From this point a single redirection is made in the turn or elbow156 (which in the presently contemplated embodiment is a smooth,radiused elbow that confines directs the flow), and the outgoing flowenters the manifold and support assembly 152 as indicated by arrow 64.As described more fully below, the manifold and support assemblyefficiently redirects the air into the annular area between the coaxialconduits, while permitting rotation of the arm.

As described herein, a “bend” within the base unit corresponds to achange in direction of between 25° and 180°, and in a particularembodiment a change in direction of approximately 90°. With thisdefinition in mind, the only bend that occurs within the base unit isessentially at turn or elbow 156. That is, within the filter box 154,although the air is redirected to the blower inlet, air within thefilter box may be considered essentially static. Air within the manifoldand support assembly 152 is carefully directed by a volute structure asdescribed below. In this sense, the base unit may be considered below.In this sense, the base unit may be considered to have a single bend.Depending upon the design of the components, the unit may be consideredto have two or three bends (or more) within the filter box 154, withinthe turn 156, which again in the presently contemplated embodiment is asmooth elbow that efficiently directs air, and within the manifold orsupport assembly 152. The redirection performed by blower is considereddifferently insomuch as the blower is the source of the static anddynamic head imparted on the airstream. Again, it is believed that byminimizing the bends or necessary redirection of the flow within thecart, greatly enhanced performances obtained with minimal head loss. Thecart may best be designed with a small and highly efficient drive motoron the blower. By way of example, current designs provide airflow with atotal head across the blower on the order of 14 in H₂O. Depending uponthe condition of the air filter, the total static head of the system mayvary between 10 in H₂O and 18 in H₂O. With such reductions in powerrequirements, current designs with an airstream volumetric flow of 900CFM may utilize a motor having a power rating of 5 Hp. However, apresently contemplated range of between 3 and 7.5 Hp motors may provideexcellent operation, particularly in an industrial context. Other powerratings and sized may, of course, be used. As noted above, in someembodiments, more than one motor and/or blower, fan or compressor may beused. Similarly the motor or motors may be fixed or variable speed.

In currently contemplated embodiments, the system may be designed suchthat the electrical requirements of the motor or motors, and othercomponents may be supplied by a 460 V, 3 phase power source. In otherembodiments, the system may be designed to receive 230 V, 1 phase power.In still other embodiments, the system may designed for 115 V, 1 phasepower. It is also contemplated, that, in addition to “professional” and“commercial” implementations, the techniques may be employed forhobbyist and other applications. Indeed, it is contemplated thatoriginal equipment or even retrofits may be made to equipment such asshop vacuum systems, existing evacuation installations, and so forth. Itis also contemplated that structures and teachings based on those setforth in the present disclosure may be utilized in specific settings toprovide airborne component collection to enhanced effect. For example,smaller systems may be based on a 1 Hp or smaller motors, with shortpositive and negative pressure conduits, such as for desk or table-topuse. Such systems may be particularly useful at workbenches, for smallerapplications, for commercial and hobbyists, and so forth.

Moreover, as will be appreciated by those skilled in the art, ingeneral, the head provided by the system will typically be a function ofsuch factors as the flow areas involved (and their relative sizes), thenumber of bends in the system (and the nature of these—smooth andcontrolled versus more turbulent or tight), the nature of surfaces inthe system, the length of the components (e.g., the arm), and so forth.The power required, then, will typically be a function of this head, andother factors, such as the flow rates, the type of air mover (e.g., fan,blower, or compressor), and the number of these. It is contemplated thatthe motor, air mover, components and so forth will be selected and set(or adjustable with ranges) to maintain efficient use of the components,particularly to maintain the air mover within a proper portion of itsperformance curve.

FIGS. 16-20 illustrate a current embodiment for the manifold and supportassembly 152 and its constituent parts. The assembly itself is bestillustrated in FIG. 16. The assembly includes an adapter 166 thatreceives the coaxial conduits 122 and 124. The adapter is rotatable withthe conduits in embodiments where an arm extends from the base unit andmay be rotated. The adapter is captured by a plate assembly 168. An airhandler 170 has an inlet 172 for receiving the airstream from the blowerand for redirecting the airstream through the annular area between thecoaxial conduits. An opening 174 is provided in which the coaxialconduits are fitted. Apertures 176 are provided for receiving fastenersor standoffs that connect the conduit assembly to the adapter.

This structure is shown in exploded view in FIG. 17. As shown in FIG.17, the plate assembly comprises an upper plate 180 and an intermediateplace 182. A lower plate 184 is positioned on a lower side of theadapter 166. The adapter has a lower peripheral flange 186 that ispositioned in a recess 188 of the lower plate 148. Thus, when the platesare assembled on either side of the adapter, the adapter is effectivelycaptured and supported between the plates, mechanically supporting thearm to which the adapter is connected. The air handler 170 has an uppersurface 190 to which the lower plate 148 is mounted during assembly ofthe system. A central passage 192 is defined through the air handler andserves to receive and communicate with the inner conduit for return flowto the air handler. The inlet 172, again, is adapted to receive flowfrom the blower and to direct this flow through the annular spacebetween the coaxial conduits.

A flow illustration of the air handler 170 is provided in FIG. 18. Asshown in FIG. 18, the air handler 170 has an inner or central passagethrough which return flow is directed. From the inlet 172, the airhandler forms a volute passage 194 that efficiently redirects flow fromthe inlet toward the annular area between the coaxial conduits asdescribed above. The inner flow to the air handler is indicated in FIG.18 by reference numeral 196. This flow is then redirected through thevolute passage as indicated by arrow 198.

FIG. 19 illustrates a present embodiment for mechanically supporting theadapter 166 within the manifold and support assembly. As shown, theadapter has a peripheral flange 186 that is captured betweenintermediate plate 182 and lower plate 184. Again, lower plate 184 isfixed, in this embodiment, to an upper surface of the air handler. Theupper plate 180, then, secures the assembly together and providesmechanical support for the adapter and thereby for the arm. In certainvariations, this arrangement may be adapted by addition of seals,bearings, and so forth. As illustrated in FIG. 20, a lower portion ofthe air handler within the central passage 192 is adapted for sealingengagement of the inner conduit. In this embodiment, two circumferentialgrooves 200 are provided that may receive seals that are compressed bythe air handler and the inner conduit (not shown in FIG. 20). The innerconduit is thus essentially “stabbed” into the air handler at the sametime that the outer conduit and adapter are mounted to the cart.

It may be noted that still other adaptations and improvements may alsobe envisaged for the system. For example, lights, flow sensors, or othercomponents may be provided on the hood to assist in the work performedor in the evaluation or control of the evacuation system. Where suchsensors are provided, closed-loop control of motor speeds, valve orlouver positions, flow rates, and so forth may be based upon sensedparameters.

It has been found that the foregoing techniques allow for greatlyenhanced capture of airborne components, such as particulate matter,smoke, fumes, gases and so forth as compared to existing technologies.In particular, for a given flow rate of gas a target velocity that isuseful in capturing such components may be provided in a larger area andfurther from the nozzle than previously possible. In particular, in apresently contemplated embodiment, a target gas velocity in a captureregion was approximately 100 ft/min, for a gas flow rate ofapproximately 900 CFM. Tests indicated that such velocities could berealized at approximately 3 ft from the nozzle inlet. It is believedthat approximately 50 ft/min was achieved at 5 ft from the nozzle inlet.These results were realized with the system described above operatingwith a 5 Hp motor.

FIGS. 21-23 illustrate this enhanced capture and velocities. Inparticular, in the illustration of FIG. 21, a cart-type extractionsystem 10 is shown as described above. The nozzle 20 is positioned neara work area 14. In this example, an operator desired to clear airbornecomponents from the work area. The smaller region 202 represents anapproximate limit for the effective capture and extraction of airbornecomponents in prior techniques. The larger region 204 represents themuch greater effective capture and extraction region afforded in acurrent embodiment described above. While the effectiveness of theextraction will depend upon factors such as particle size, the graphicillustration of FIG. 21 has been found to be borne out in actualtesting.

FIGS. 22 and 23 are arrow diagrams developed through computer simulationof the same system. As shown in FIG. 22, the positive pressure airstream 206 may be represented by generally parallel flow arrows 208within the confines of the conduits (not shown). As noted above, in thisembodiment, concentric conduits were used, such that the positivepressure air stream 206 is confined in an annular region, althoughmultiple and/or non-concentric conduits may also be used. As the airstream exits the nozzle (not shown), it is diverted radially, as shownby arrows 210. Such diversion is assisted by the geometries of thenozzle elements, as described above. Following deflection, then, thestream diverges, as indicted by arrows 212 to form a region that isgenerally protected from perturbation, allowing for enhanced capture bythe negative pressure air stream. It may be noted that in certainapplications, such as welding applications utilizing shielding gases,this region definition may allow for improved component capture,cooling, and other benefits without perturbing the flow andeffectiveness of shielding gases used in the welding process.

FIG. 23 illustrates the flow of gas back into the nozzle (again notshown) as part of the negative pressure air stream 214. As indicated byarrows 216, the velocity of gas (and airborne components) begins at somedistance from the nozzle entrance, as described above. The gas thenconverges near the entrance of the nozzle, as indicated by arrows 218,and ultimately is drawn into a generally linear path in the conduits, asindicated by arrows 220. Here again, it has been confirmed throughactual testing that desired velocities may be obtained, for a given gasflow rate, at enhanced distances 222 from the nozzle entrance.

While only certain features of the disclosure have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the disclosure.

1. An extraction system comprising: a hood having an outer shroud and aninner shroud, the inner shroud being at least partially disposed in theouter shroud to define an annular area therebetween for receiving apositive pressure gas stream, the inner shroud further including asingle peripheral flange at a lower edge thereof for directing thepositive pressure gas stream radially outwardly around a work area oncethe positive pressure gas stream passes a lower peripheral edge of theouter shroud, the inner shroud being configured to draw airbornecomponents from the work area.
 2. The system of claim 1, wherein theperipheral flange is substantially perpendicular to a centerline of theinner shroud.
 3. The system of claim 1, wherein at least a portion of atleast one of the inner and outer shrouds is movable with respect to theother to permit adjustment of flow of the positive pressure gas stream.4. The system of claim 1, wherein a gap between the lower peripheraledge of the outer shroud and the peripheral flange is adjustable.
 5. Thesystem of claim 1, comprising a manifold for distributing the positivepressure gas stream around the annular area.
 6. The system of claim 1,comprising means for imparting a swirling motion to the positivepressure gas stream.
 7. The system of claim 6, wherein the means isdisposed in the annular area.
 8. The system of claim 1, wherein theinner shroud and the outer shroud are coupled to one another by at leastone standoff.
 9. The system of claim 1, wherein the inner shroud has aneffective inner diameter d and the single peripheral flange has aneffective outer diameter D, and wherein a ratio of d/D is between about0.25 and 0.75.
 10. The system of claim 9, wherein the ratio d/D is about0.5.
 11. An extraction system comprising: a hood having an outer shroudand an inner shroud, the inner shroud being at least partially disposedin the outer shroud to define an annular area therebetween for receivinga positive pressure gas stream, the inner shroud further including asingle peripheral flange at a lower edge thereof for directing thepositive pressure gas stream radially outwardly around a work area oncethe positive pressure gas stream passes a lower peripheral edge of theouter shroud, the inner shroud being configured to draw airbornecomponents from the work area, and a lip formed around a lower edge ofthe outer shroud to aid in directing the positive pressure gas stream.12. The system of claim 11, wherein the peripheral flange issubstantially perpendicular to a centerline of the inner shroud.
 13. Thesystem of claim 11, wherein the inner and outer shrouds are disposedconcentrically.
 14. The system of claim 11, wherein a ratio of aneffective inner diameter of the inner shroud to an effective diameter ofthe flange is between about 0.25 and 0.75
 15. The system of claim 14,wherein the ratio of the effective inner diameter of the inner shroud tothe effective diameter of the flange is about 0.5.
 16. The system ofclaim 11, wherein the lip comprises a radiused lip having a a radius ofapproximately 0.25 inches.
 17. The system of claim 11, wherein the lipextends at an angle of approximately 45 degrees.
 18. The system of claim11, wherein the lip comprises two radiuses joined by a transition point.19. An extraction system comprising: a hood having an outer shroud andan inner shroud, the inner shroud being at least partially disposed inthe outer shroud to define an annular area therebetween for receiving apositive pressure gas stream, the inner shroud further including asingle peripheral flange at a lower edge thereof for directing thepositive pressure gas stream radially outwardly around a work area oncethe positive pressure gas stream passes a lower peripheral edge of theouter shroud, the inner shroud being configured to draw airbornecomponents from the work area, wherein a ratio of an effective innerdiameter of the inner shroud to an effective diameter of the flange isbetween about 0.25 and 0.75
 20. The system of claim 19, wherein theratio of the effective inner diameter of the inner shroud to theeffective diameter of the flange is about 0.5.